AfterEffects

Set composition background color

The default background color for the Composition panel is black, but you can change the color at any time.

 Choose Composition > Background Color, and then click the color swatch or use the eyedropper to pick a color.
Note: When you add one composition to another (nesting), the containing composition’s background color is preserved, and the nested composition’s background becomes transparent. To preserve the nested composition’s background color, create a solid-color layer to use as a background layer in the nested composition.